N400 Citizenship application

[shahkr]

Is filing incometax return is mendatory?
what If incometax return is not filed while applying for naturalisation.

I have greencard based on marriage.What will happen if I have not filed tax return for any reason?

[paulwim]

Did your husband file for both of you? It is the law in this country that you must file for Income Tax and yes, the USCIS take it very serious!. If you worked while in this country and were paid and you did not file your taxes, you might be denied citizenship. They ask for these things to proove that you are abiding by the laws of the US.
My husband was out of work for over a year with no income and I was the only one working. When I filed my taxes I still had to include him on the IRS forms but with $0 as income. If he is asked if he filed his taxes he can always say yes because the IRS has record that he made no money. But if he worked and did not file his taxes, they will come after him.
Hope this helps